Magnetotelluric Imaging of the Lithospheric Structure of the Southern Oklahoma Aulacogen: Evidence for Long‐Term Weakening Caused by Rifting
-
Published:2023-06
Issue:6
Volume:128
Page:
-
ISSN:2169-9313
-
Container-title:Journal of Geophysical Research: Solid Earth
-
language:en
-
Short-container-title:JGR Solid Earth
Author:
Chase B. F. W.1ORCID,
Unsworth M. J.1,
Atekwana E. A.2,
Evans R. L.3ORCID,
Zhu J.3ORCID
Affiliation:
1. Department of Physics University of Alberta Edmonton AB Canada
2. Department of Earth and Planetary Sciences University of California Davis Davis CA USA
3. Woods Hole Oceanographic Institution Falmouth MA USA
Abstract
AbstractMagnetotelluric data were used to study the lithosphere structure of the Southern Oklahoma Aulacogen (SOA). Inversion of the data revealed two low resistivity anomalies beneath the SOA. The first is located in the depth range 0–90 km in the crust and upper lithospheric mantle. The second extends from a depth 100 km to the base of the lithospheric mantle and extends away from the SOA to the ends of the profile. The cause of low resistivity anomalies is discussed in relation to the tectonic evolution of the region and recent laboratory experiments on rock conductivity. The first anomaly is attributed to the combination of (a) water present in mantle minerals and (b) the formation of hydrous mineral phases by interactions between a plume and the lithosphere during rifting. Grain size reduction and fabric alignment from deformation during the Ancestral Rocky Mountain (ARM) orogeny may have also contributed to the low resistivity. This enrichment phase may have mechanically weakened the lithosphere and allowed deformation to occur during the ARM orogeny. The low resistivity of the deeper anomaly is attributed to a fluorine‐enriched phlogopite layer that is also coincident with an observed seismic mid‐lithosphere discontinuity (MLD). A lithosphere keel of mantle minerals enriched in water underlies this layer and may have formed by accretion of the plume head to the lower lithosphere after rifting, which also rethickened the lithosphere to its present‐day depths. The MLD may then reflect a melt layer along a paleo lithosphere‐asthenosphere boundary entombed during the accretion.
Publisher
American Geophysical Union (AGU)
Subject
Space and Planetary Science,Earth and Planetary Sciences (miscellaneous),Geochemistry and Petrology,Geophysics
Reference168 articles.
1. The Saharan Metacraton
2. Relationships Between Lithospheric Structures and Rifting in the East African Rift System: A Rayleigh Wave Tomography Study
3. Halogens in volcanic systems
4. Early and middle Paleozoic history of the Anadarko basin;Amsden T. W.;Geological Society of America Abstracts with Programs,1982
5. Behavior of trace elements during magmatic processes—A summary of theoretical models and their applications;Arth J. G.;Journal of Research of the U. S. Geological Survey,1976